This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Over the past two years, we have developed Isotopic Detection of Aminosugars With Glutamine (IDAWG) as a very powerful method for quantifying the amounts of N- and O-glycans in biological samples. This method is based on metabolic (in vivo) labeling of amino sugars with 15N atoms. Mass spectral analysis of the glycans containing these atoms contans quantitative information regarding the proportions of the molecules that are derived from light (natural abundance) and heavy (isotopically enriched) precursors in the growth medium. Extraction of this quantitative information is not trivial, especially for high-throughtput sprectral data with significant noise and/or signals due to contaminating molecules. We are developing software to process mass spectral data generated by in vivo isotopic labeling of glycans using methods related to IDAWG.